Preheat the oven to 350°F (175°C) and spray a 9×13-inch baking dish with cooking spray.
In a large skillet over medium-high heat, brown the ground beef until no longer pink, breaking it up with a spatula.
Add the diced onion and diced red bell pepper to the skillet and cook about 3 minutes until slightly softened; drain any excess grease.
Stir in 1–2 tablespoons taco seasoning, the Rotel tomatoes, drained black beans, drained corn, and 1/2 cup salsa.
Add the softened cream cheese to the skillet and stir until it melts and combines into a cohesive filling, then remove from heat.
Place 5 corn tortillas in the bottom of the prepared baking dish, overlapping as needed to cover the surface.
Sprinkle about 1/2 cup of shredded cheese over the tortillas, then spread half of the beef mixture evenly on top.
Top with the remaining 5 tortillas, then add the rest of the beef mixture evenly over them.
Finish by sprinkling the remaining shredded cheese over the top.
Bake uncovered for 25–30 minutes until the casserole is hot and bubbly and the cheese is melted.
Remove from the oven and serve with any desired toppings.
